Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 3/31/2023
Public

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?gemm_pack

Performs scaling and packing of the matrix into the previously allocated buffer.

Syntax

call sgemm_pack (identifier, trans, m, n, k, alpha, src, ld, dest)

call dgemm_pack (identifier, trans, m, n, k, alpha, src, ld, dest)

Include Files
  • mkl.fi
Description

The ?gemm_pack routine is one of a set of related routines that enable use of an internal packed storage. Call ?gemm_pack after you allocate a buffer whose size is given by ?gemm_pack_get_size. The ?gemm_pack routine scales the identified matrix by alpha and packs it into the buffer allocated previously.

NOTE:

Do not copy the packed matrix to a different address because the internal implementation depends on the alignment of internally-stored metadata.

The ?gemm_pack routine performs this operation:

dest := alpha*op(src) as part of the computation C := alpha*op(A)*op(B) + beta*C

where:

  • op(X) is one of the operations op(X) = X, op(X) = XT, or op(X) = XH,
  • alpha and beta are scalars,
  • src is a matrix,
  • A , B, and C are matrices
  • op(src) is an m-by-k matrix if identifier = 'A' or 'a',
  • op(src) is a k-by-n matrix if identifier = 'B' or 'b',
  • dest is an internal packed storage buffer.

NOTE:

For best performance, use the same number of threads for packing and for computing.

If packing for both A and B matrices, you must use the same number of threads for packing A as for packing B.

Input Parameters
identifier

CHARACTER*1. Specifies which matrix is to be packed:

If identifier = 'A' or 'a', the routine allocates storage to pack matrix A.

If identifier = 'B' or 'b', the routine allocates storage to pack matrix B.

trans

CHARACTER*1. Specifies the form of op(src) used in the packing:

If trans = 'N' or 'n'  op(src) = src.

If trans = 'T' or 't'  op(src) = srcT.

If trans = 'C' or 'c'  op(src) = srcH.

m

INTEGER. Specifies the number of rows of the matrix op(A) and of the matrix C. The value of m must be at least zero.

n

INTEGER. Specifies the number of columns of the matrix op(B) and the number of columns of the matrix C. The value of n must be at least zero.

k

INTEGER. Specifies the number of columns of the matrix op(A) and the number of rows of the matrix op(B). The value of k must be at least zero.

alpha

REAL for sgemm_pack

DOUBLE PRECISION for dgemm_pack

Specifies the scalar alpha.

src

REAL for sgemm_pack

DOUBLE PRECISION for dgemm_pack

Array:

 

trans = 'N' or 'n'

trans = 'T', 't', 'C', or 'c'

identifier = 'A' or 'a'

Size ld*k.

Before entry, the leading m-by-k part of the array src must contain the matrix A.

Size ld*m.

Before entry, the leading k-by-m part of the array src must contain the matrix A.

identifier = 'B' or 'b'

Size ld*n.

Before entry, the leading k-by-n part of the array src must contain the matrix B.

Size ld*k.

Before entry, the leading n-by-k part of the array src must contain the matrix B.

ld

INTEGER. Specifies the leading dimension of src as declared in the calling (sub)program.

 

trans = 'N' or 'n'

trans = 'T', 't', 'C', or 'c'

identifier = 'A' or 'a'

ld must be at least max(1, m).

ld must be at least max(1, k).

identifier = 'B' or 'b'

ld must be at least max(1, k).

ld must be at least max(1, n).

dest

POINTER.

Scaled and packed internal storage buffer.

Output Parameters

dest

Overwritten by the matrix alpha*op(src).

See Also